Abstract
The synthesis and the anti-HIV activity of two mononucleoside phosphotriester derivatives of 3′-azido-2′,3′-dideoxythymidine (AZT) and 2′,3′-dideoxyadenosine (ddA) incorporating a new kind of phosphate protecting group, namely S-pivaloyl-4-thiobutyl (tBuSATB), are reported.